1. Field of the Invention
The invention relates to trailing arm suspensions. In one of its aspects, the invention relates to a trailing arm suspension with a trailing arm having a pair of plates rigidly connected together by clamped spacer tubes. In another of its aspects, the invention relates to a trailing arm suspension with a bolted trailing arm.
2. Description of the Related Art
Trailing arm suspensions are well known and commonly used in heavy-duty vehicles, such as semi tractor-trailer configurations. The trailing arm suspensions can be used for the drive axle of the tractor or the axles of the trailer.
A typical trailing arm suspension comprises a trailing arm having one end pivotally connected to the vehicle frame through a frame bracket and another end connected to the vehicle frame by an air spring. The trailing arm supports an axle to which the vehicle wheels are mounted. Road-induced reaction forces acting on the wheels are controlled by the pivoting of the trailing arm in response to these forces, with the forces being resisted by the air spring.
Given that a typical tractor-trailer has multiple trailing arm suspensions and subject to regulated weight limits, there is a continuous need to reduce the weight and cost of the trailing arm suspensions while maintaining or improving the operating characteristics. Also, the high volume of trailing arm suspensions also exerts continuous pressure for improved and simplified suspension designs to reduce overall costs, including assembly and maintenance costs.
The invention relates to a trailing arm suspension for supporting a vehicle frame on ground supported wheels wherein a pair of spaced trailing arm assemblies carries an axle, and each of the trailing arm assemblies comprises a trailing arm having one portion adapted to be pivotally mounted to the vehicle frame and a spring for resisting the pivotal movement of the trailing arm relative to the vehicle frame. According to the invention, each trailing arm includes spaced side plates, at least two spacers extending between the spaced slide plates and fasteners extending through the side plates and the at least two spacers clamping the spacers between the side plates to form a rigid beam. Preferably, the spacers are the sole connection between the spaced side plates.
In a preferred embodiment of the invention, the spacers have a tubular body defining an axial passage and opposing ends, with each opposing end abutting one of the side plates, and the fasteners include a bolt which extends through the axial passage and a nut threaded onto the bolt. Preferably, washers are positioned between the spacers and the side plates. At least one of the at least two spacers further comprise a bushing formed by an outer sleeve, an inner sleeve received concentrically within the outer sleeve, and an elastomeric annulus disposed between and bonded to the inner sleeve and the outer sleeve for resilient movement of the inner sleeve with respect to the outer sleeve.
In one embodiment, a torque resistant connector is joined to and extends between the trailing arms to resiliently resist relative rotation of one of the trailing arms with respect to the other. In one embodiment, the torque resistant connector is mounted to the trailing arms through at least one of the at least two spacers. The torque resistant connector is connected to the at least one of the at least two spacers through spaced plates, each of which has an opening in which the torque resistant connector is mounted.
In another embodiment, a base plate spans and is mounted to the side plates of the trailing arm and the torque resistant connector is mounted to the base plate though a resilient coupling. The torque resistant connector is connected to the base plate through spaced plates, each of which has an opening in which the torque resistant connector is mounted, and the resilient coupling comprises a bushing disposed between the base plate and the spaced plates. The resilient coupling further comprises a second bushing on the opposite side of the base plate than the first bushing and a fastener extending through the spaced plates, base plate, and the first and second bushings. A frame bracket is adapted to mount to the frame and pivotally mounts the trailing arm. Alternatively, the torque resistant connector can be mounted to the trailing arm beneath the frame bracket.
In a preferred embodiment of the invention, the axle is connected to the trailing arm through at least one of the at least two spacers. Preferably, the at least one of the two spacers connecting the axle to the trailing arm is a resiliently bushed connector to permit articulation of the trailing arm with respect to the axle. The axle can be mounted to the at least one of the at least two spacers through a wrapper band that compressively mounts the axle to the at least one spacer.
In a preferred embodiment of the invention the spring is an air spring.
Other objects, features, and advantages of the invention will be apparent from the ensuing description in conjunction with the accompanying drawings.